1. Field of the Invention
This invention relates generally to sports equipment, and more particularly to multi-purpose backpack frames.
2. Description of the Prior Art
Backpacking is a heathful and invigorating sport enjoyed by people all over the world. When backpacking, a person hikes into the backcountry while carrying all of the supplies and equipment that he or she needs in a frame-mounted knapsack.
Because backpackers usually wish to carry as little weight as possible, the bedding materials carried by most backpackers is quite spartan. For example, a backpacker may carry only a sleeping bag and a ground cover. Backpackers who wish to have greater creature comforts may additionally carry a foam pad or an inflatable mattress.
Most backpackers will agree that sleeping on the ground, even with a foam pad or air mattress, is far from the most healthful and restful sleeping arrangement. The hard, bumpy, sloped, and irregular ground surfaces upon which backpacker must often sleep causes many backpackers to awaken many times during the night. The lightweight foam pads which some backpackers use are usually too thin to provide a truly comfortable sleeping surface. Air mattresses are often comfortable at the time the backpacker retires for the evening but are usually flat by the time the weary and sore backpacker arises in the morning.
One solution to this problem is for the backpacker to bring along a folding cot. However, for the aforementioned weight consideration reasons, most backpackers prefer not to do this.
A solution to this dilemma has been suggested by a number of inventors who propose to form a cot out of an item already being carried by the backpacker, namely the backpack frame. For example, in U.S. Pat. No. 4,056,857 of Quantz a convertible backpack and cot is described which has two mutually slidable frame portions held together with a plurality of fastening straps. U.S. Pat. No. 3,846,855 of Peterson teaches a convertible backpack and cot including a unitary extensible frame having telescoping side and end portions.
A problem with convertible backpack/cots of the prior art is that their strength-to-weight ratio tends to be rather low. The lightweight prior art backpack/cots tend to be unsteady and unsuited for rugged use. The more sturdily constructed prior art backpack/cots tend to be too heavy to be practicable for backpacking applications.
A further problem with backpack/cots of the prior art is that they are not adjustable in length. As a consequence, prior art backpack/cots have to be designed and built to comfortably support the tallest and heaviest conceivable user of the cot, with the result that the backpack/cots are heavier and more expensive than they need to be.